Use concurrent uunordered map for parameter set registry
Rename Registry::setID() to setProcessParameterSetID()
Merge pull request #1555 from wmtan/UseConcurrentUnorderedMapForParameterSetRegistry

Multithreading fixes -- Use concurrent unordered map for parameter set registry
Merge remote-tracking branch 'origin/CMSSW_7_0_X' into CMSSW_7_0_X